Spray gun



Oct. 27, 1931.

P. 8. CASE SPRAY GUN Filed June 4, 1929 ATTORNEYS Patented Oct. 7 27, '1931 um'rno STATES PATENT OFFICE PHILIP s. CASE, or NIAGARA FALLS, new You, Assrenon. 'ro memo ,gn'rmunercAL comm, A conronA'rIon or war vInomIA srnAY dun Application filed June 4, 1929. Serial No. 868,298.

7 My invention relates to spray guns for producing a low. velocity-spray of commmuted solids combined with liquid and gas so as to form moistened coatings of the solid material.

One of the purposes of my invention is to provide devices which will produce coatings of powdered solids on fragile ob ects, which objects are injured by high velocity sprays.

Another purpose of my invention is to provide devices which are capable of producing a composite spray consisting in part of moistened solids and gas of high moisture content .and in part of moistened solids of low moisture content.

Another purpose of my invention is to provide a device of few parts and of simpleconstruction which may be incorporated in a small sized nozzle in which the constituentsof the s ray may be easily regulated and disassem lage of the device for the pur ose of cleaning, may be quickly and easily e ected.

In the drawings constituting a part hereof,

Fig. 1 is a view in elevation and partially in cross section of aspray gun,

Fig. 2 is an elevational view of a'nozzl e Fig. 3 is an elevational view of a modified form of'nozzle,

Fig.4is a cross sectional view of the head of the gun taken along the line IVIV of Fig.

i 1, and

Fig. 5 is a cross sectional view of .a ortion of the head of the gun taken along t e line VV of Fig. 4. a g

The spray gun is capable of being used with gases, liqulds and solids of vanous kinds and densities but will be described in connection with its use for coating sand molds with coatings of metal owders and a binder of sugar solution in w 'ch air is used to produce the suspensions of solids and liquid.

' The spray gun has a handle portion which may comprises. pipe 1 for conducting m1xtures of solids and air, apipe 2 for conducting liquid and a pipe 3 for conducting air. The pipes are held together by a clam 4 near one end of the pipes and by screwing t e other ends into a threaded head 5 which is provided with bores 6, 7 and 8 corresponding to the passages in the pipes 1,2 and 3 respectively.

Valves 10 and 11 are mounted on the outer ends of pipes 2 and 3 for regulating the supply of liquid and air. The bore 6 and its corresponding passage through the pipe 1 are provided with a wear-resisting lining to prevfint the wearing away of the metal arts of t e n. rubber lining '12 which'is secured in the ip'e in any convenient manner and extends mm the nipple 13 to the discharge terminus of the passage 6 in the head 5. A suspension of comminuted solids in air is supplied to the gun through a pipe which is connected to the nipple 13, a source of liquid under pressure is connected to the gun through the union'14 and a sup ly of air under pressure is connected throng the union 15 to the pipe 3.

The head 5 may be formed so as to ro- 'ect the spray at an angle to the axis of the andle. On the extremity of the head 5, is a. nip le 20 as shown in Fi s. 2,3 and 5 which orms the extremity o the bore 6. The nipple is detachably mounted on the head byproviding a screw conn'ection.--A small groove 21, as shown in Figs. 2 and 3, preferably about of an inch across and about of an inch long is cut in the exterior surface of the nipple 20 parallel to the axis of the passage 6. The groove 21 provides a mixingchamber and a discharge port for the 21-is connected with forking grooves 22 and 23. The liquid binder is supplied to the groove 21 through the groove 22 and air is supplied through the groove 23. An exterior sleeve 24 which is given a snug sliding fit with the nip 1e 20 has a smoothly faced flange- 25 which is mounted on a corresponding facing of the member 5 by means of a nut 26. It has been found that a short small roove 21 does not tend to become filled w th an accumulation of hardened binder and that mixtures of solids and liquid do not tend to collect on the end of the nozzle and clog the small port. 7

Referring to Fig. 4, an annularly disposed groove 27 which extends only partly around the nipple is cut in the facing of the member 5 so as to form a connection between the terminus of the bore-7 and the groove 22;

The lining may consist o a' gum and a similar connection groove 28 extends between the terminus of the bore 8 and the groove 23. The seating of the flange 25 on the facin leakage 'air or liquid from the passages 27 and 28,-and the sliding fit of the sleeve 24 on the nipple 22 prevents leakage of air and 1i uid from the grooves 22 and'23.

hifiicient operation and control of the spray depends in large measure upon clean, free passages for air and liquid binder. Efficiency and constant operation of the gun over long periods is facilitated by the arrangement of the small passages which are formed between the surfaces of stationary and demountable parts. Their arrangement provides means to open the small passages lengthwise and to expose to view the exact condition of the passages.

The nipple 20 is preferably provided with at least two mixing chambers and discharge ports 21 and with corresponding forking air and liquid grooves 22' and 23 so that each of the grooves 21 has a. connection with the air supply and a connection with the liquid supply. Where two ports 21 are used, they are preferably positioned diametrlcally opposite each other but more than two or less than two discharge ports may be used and they may be located in the end of the nozzle in other positions than those shown 1n the drawing. Two ports 21 give good results and it has been found in practice that. less frequent adjustment of the liquid and air is necessary and that the coating of irregular surfaces is more easily controlled with a small number than with a large number of ports 21.

Where the discharge of the mixture of 1iquid and air consists of a small number of grobves 21, as for example two grooves, the

composite spray which is formed externally of the nozzle, consists of two portions of parts 0 solids suspended in air which contain a relatively large amount. of moisture. The remainder of the spray is drier.. The relative amount of moisture in the two moisture-rich portions may also be varied by rotating the gun about the axis of the nozzle 20 so that the spray of heavy solids and air will descend more or less away from one jet of mixed liquid and gas and toward the other. In tlus way, the quality of the composite spray may be changed so that one portion of the spray.-

will be largely solids and air and another portion will be largely liquid and air. The

latter regulation is useful to produce various de ees of wetness. in applying difierent f the coating.

In the normal 0 eration of the n, the spray of solids an air projected Irom the passage 6 is a low-density low-velocity mixture of large volume and the spray at the nozzle from the grooves 21 is a comparatively high-velocity low-density spray of small vol ume. Because of the tendency of the sprays of the head member 5 prevents 4 the -solid particles.

to expand and diffuse they combinewithin a short distance of the nozzle, the spray of higher velocity'supplying energy to carry on the solid particles at a velocity. commensurate with their nozzle velocity. The spray of liquid and air also produces a turbulence which helps to produce a moistening of all Because of the high density of the solids and the low velocity of the spray of solids and air, the solids tend to segregate in the lowest parts of the passage 6. Therefore, the gun is i usually operated sothat the rooves 21 are in a vertlcal plane so that the ower of the two sprays will commingle directly with the most dense mixture of air and solids. When the position of the surface to be coated requires that the nozzle be. turned through an angle,

I provide a nozzle as shown in Fig. 3 with the forked grooves 22 and23 curved around the nozzle so as to connect with ooves 21. Thus, the grooves are displaced 't rough an are required by the new position of the gun.

A regulated andconstant supply of a lowdensity low-velocity mixture or cloud of finely divided metal particles and air may be produced, by any convenient means and conducted through the passage 6. In operation the velocity of this mixture may conveniently be regulated so that the stream of solids will.travel 8 or 10 inches from. the nozzle before the general course of the stream is vertical. binder. are next regulated by opening the valves 10 and-11 so that a spray of the desired liquid content and sufiicient velocity is produced to moisten substantially all of the The supplies of air and liquid solids at a short distance from the nozzle,

say 4 or. 6 inches. -To produce a spray hav-.

ing a small portion of drier solids and a portion of more moist solids than that contamed as an average in the spray, the nozzle may be held close to the surface to be coated or the nozzle may be turned so that the grooves 21 are moved out of the vertical plane. In making a coating of powdered metal the gun is usually moved back and forth or given a rotary motion so that the coating of solids on all parts of the coated mold will have-a uniform moisture content.

Although-l have described certain specific a bore for conducting gas, a bore for conducting liquid, and a. bore for conducting a mixture of solids and gas, a terminal memher on the head haying! a discharge orifice ducting liquid and a for the mixture of solids and gas, said member having a groove therein to conduct gas, a groove to conduct liquid and a communieating groove to mix gas and liquid, and

,for the mixture of solids and gas, said member having a groove therein to conduct gas, a groove to conduct liquid and a communicating groove to mix gas and liquid, and

means in said head to form separate connections between the gas groove and bore and the liquid groove and bore respectively.

3. A spray gun comprising a head having a bore for conductin gas, a bore for con- %)ore for conducting a mixture of solids and gas, a projecting member on said head having a groove for mixing and discharging a mixture of liquid and gas, a faced portion onsaid head cutting across the gasbore and the liquid bore and having annularly dis osed grooves for conducting gas and liqui respectively, said projecting member having grooves connecting the annularly disposed grooves with the discharginggroove, a closely fitting sleeve on said projecting member forming-passages with the grooves in the projecting member, a flanged member on said sleeve seated on the faced portion of said head so as to form passages with the grooves in. the head, and means to engage the flange and secure the sleeve to the head.

4. A s ra gun com rising a head, a tubular terr'mna member aving an axially disposed bore for discharging a mixture of solids and gas, means on saidtubular terminal member to mix 1i uid and gas, means to v conduct liquid to sai mixer and means to conduct gas to said mixer, said mixing means having a discharge port situated at the side of the axial terminus of the bore and directed parallel to the axis of said bore.

5. A spra gun com lar termma member aving an axially disposed bore for discharging a mixture. of solids and gas, means on said tubular terminal member to form mixers for 1i uid and gas, means to conduct liquid to sai mixers, and means to conduct gas to said mixers, said mixers being disposed annularly around said axial bore and aving discharge ports rising a head, a tubuand gas, means to conduct liquid to said mixers, and means to conduct gas to said mixers, said mixers being spaced equally and annularly around the dlscharge end of said axial bore, each one of said mixers having a discharge port directed parallel to the axis of the bore.

7. A spray gun com rising a head, a tubular terminal member aving an axially disposed bore for discharging a' mixture of solids and gas, means on said tubular member to form a plurality of mixers for liquid and gas, means to conduct liquid to said mixers, and means to conduct gas to saidmixers, said mixers being spaced equally, diametrically and annularly around the terminus of said axial bore, each one of said mixers having a discharge port directed parallel to the axis of said bore.

8. A spray gun comprising a handle, having a passage for conducting a mixture of solids and gas, a passage for liquid and a passage for gas, means on said handle to regulate the supply of liquid and gas, a head having bores coextensive with said passages, a faced portion on said head having a groove connected with the gas bore and a groove connected with the liquid bore, a demountable tubularterminal member having a forked groove in the exterior surface thereof with branches connected with the liquid and gas grooves of the head and one branch forming a mixing chamber for liquid and gas and a discharge port for said mixture, a tted sleeve around said terminal member, a flange on said sleeve adapted to form a seal with the faced portion of said head, and means engaging said head and flange to secure the sleeve.

In testimony whereof, I aflix m si PHILIP ature. ASE.

around the discharge end of the axial bore I and directed parallel to theaxisof said bore;

6. A spra gun comp'risinga head, a tubular termina member having an axially dis- 1 posed bore for discharging a mixture of 

